The present invention is related generally to wireless communication devices and connectable external accessories, and more particularly, to a system and method for detecting when an external accessory has been connected to the wireless communication device and for identifying the type of external accessory connected.
Modern wireless communication devices, such as cellular telephones, are designed so that the user may connect external accessories to the cellular telephone, enabling the user to use the cellular telephone in a wider range of applications than if the cellular telephone were used by itself. For example, a headset accessory may be connected to some cellular telephones so that a microphone and earpiece are positioned in proximity of the user""s mouth and ear, respectively, to permit hands-free operation of the cellular telephone. Another example of a common external accessory connectable to a cellular telephone is a carkit accessory that allows the cellular telephone to be used while driving an automobile without the inconvenience of holding the cellular telephone. The kit includes a microphone that can be attached to a convenient location within the automobile, and the kit is connected to the automobile""s audio system so that the audible signals produced by the cellular telephone can be heard over the speakers of the audio system.
Other examples of common external accessory devices include a battery charger to recharge the internal battery of the wireless communication device and a computer interface that allows connection of a personal computer or laptop to the wireless communication device via a PCMCIA (Personal Computer Memory Card International Association) interface. Numerous other types of external accessories are available. These external accessories are connected to the wireless communication device by an extension cord having a fitting at its end. An accessory port of the wireless communication device receives the fitting, and in this fashion, the external accessory is electrically and communicatively coupled to the wireless communication device.
However, for a variety of reasons, there is an ongoing need to find a satisfactory way for the wireless communication device to identify when an external accessory has been coupled to the accessory port and to identify the type of external accessory. For example, if the user of the wireless communication device wishes to increase the volume of a call, the wireless communication device will need to know if the volume adjustments being made by the user are being directed towards the wireless communication device internal speaker or to a speaker of an external accessory. Without this ability to identify when and what kind of external accessory is coupled, the user may be mistakenly increasing the volume of the internal speaker within the device, instead of the volume of the speaker of the external accessory that the user intended to adjust. The present invention provides solutions to these problems, as will be apparent from the following detailed description and accompanying figures.
The present invention is embodied in a system and method directed to sensing when an external accessory is coupled to a wireless communication device, and to identifying the type of external accessory. In one embodiment, the wireless communication device includes an accessory port that allows an external accessory to be coupled to the wireless communication device, the accessory port including at least one data line, and a processor to sense activity on the data line when the external accessory has been coupled. The processor senses identification data associated with the external accessory to identify the external accessory.
In an exemplary embodiment, the data line is a portion of a pulse code modulation (PCM) port. The processor generates a clock signal coupled to the accessory port. The external accessory transmits identification data to the wireless communication device over the data line as determined by this clock signal.
In one embodiment, the phone detects activity on the data line as indicative of whether the external accessory is coupled to the wireless communication device. Also, the presence of voltage on an input line of the phone""s accessory port is indicative of whether the external accessory provides power to the phone. The identification data includes an identification code of the external accessory. The processor identifies the type of external accessory by comparing the identification code with stored codes corresponding to a plurality of external accessories. The invention allows a wireless communication device to identify a carkit, headset, computer interface, battery charger, and other types of external accessories.